Recently, there have been brought into practical use image forming apparatuses of an electrophotographic system which enable copying or printing full-color images. A secondary transfer system using an intermediate transfer material is advantageous as a transfer system of full-color images onto transfer material, in terms of paper-free copying and full copying feasibility and is broadly used.
The secondary transfer system using an intermediate transfer material is a system in which the respective color images of yellow (Y), magenta (M), cyan (C) and black (Bk) which are successively formed on an electrostatic latent image carrier are transferred onto an intermediate transfer material and superposed after which a transferred full-color toner image is transferred in one transfer operation onto a final transfer material, and is also called a intermediate transfer system.
Thermoplastic resins such as polyimide resin or polyamide resin, used in intermediate transfer materials have not been capable to achieve sufficient secondary transferability, specifically in an atmosphere of high temperature and high humidity. To overcome the foregoing problem, there was attempted a process by using an intermediate transfer material of a multilayer structure. Specifically, there was studied reduction of the surface energy of a surface layer. However, enhancement of the secondary transfer rate resulted in lowering of abrasion resistance and sufficient improvement was not achieved, as described in JP-A Nos. 2003-330216, 2004-21188, 2004-4504 and 2005-99182 (hereinafter, the term JP-A refers to Japanese Patent Application Publication).